The over-all objective is the synthesis and investigation of new small-ring heterocyclic systems of potential value as cancer chemotherapeutic agents. Principal emphasis is placed on three-membered ring, cyclic urea derivatives (diaziridinones), a functionality showing selective reactivity both as a mild oxidizing agent and as a site for nucleophilic attack. Possible relationships to current concepts in cancer chemotherapy are examined. The initial objective is to find ways to synthesize diaziridinones with a wide range of substituents. Proposed methods include new approaches to the cyclization of substituted ureas. Attention is directed to a new derivative of ureas, a N-dialkylsulfonium salt (dialkyl-(N-alkyl-N-carboxamidoamino)sulfonium halide). Possible cyclization of these species by base may constitute a general method for the preparation of diaziridinones, with potential applicability to other small-ring heterocyclic systems. Investigation of the properties and reactions of the N-sulfonium derivatives will also be undertaken. A further objective is information on reactivity of diaziridinones with emphasis on three aspects: a) rate and product information on reactions of diaziridinones with a variety of substrates of biological importance; b) investigation of ring-opening and rearrangement reactions; c) examination of the competition between nucleophilic attack and oxidation reduction. The synthetic and structure-reactivity information will be applied to the selection and preparation of a series of compounds for testing as cancer chemotherapeutic agents.